In the foam industry, which includes the foaming of polymeric composition and fabrication of the resulting foam material into mattresses, seat cushions, and the like, a standard indication of firmness of such materials is known as the R.M.A. compression value. By way of information, R.M.A. is the abbreviation for Rubber Manufacturers Association, and the foam industry generally conforms to this association's specifications for the compression test to be used in measuring foam material for compression modulus.
Such test involves measuring the weight necessary to produce a 25% indentation in a sample of foam by bringing a flat circular plate having an area of fifty square inches and a preload of one pound in contact with the surface of the foam piece to determine the initial thickness thereof. The material is then compressed 25% of the original height by increasing the load on the plate. The final total load is recorded as the R.M.A. compression value.
It has become conventional in the foam industry to continuously extrude foam in large buns, from which mattresses and cushions are later cut. It is very advantageous to be able to determine the compression value of a bun while it is being run or at sometime before it is cut, rather than after the bun has been sawed and cut into smaller pieces, or to easily measure and test a sample while it is being stored. Heretofore, such measurements have not been possible, because the measuring devices have required removal of a sample or slab of foam to a testing site, where the foam is laid on a flat plate, then the afore-described procedure for the R.M.A. compression value test is carried out. It is easily seen that this requires considerable interruptions in the normal flow of material and continuous testing or spot-checking at any time and at any place is not possible.
One example of an attempt to provide a more economical compression testing apparatus is illustrated and described in the U.S. Pat. No. 2,913,899 to Wohler, which does provide a portable device from the standpoint that the device may be moved around. However, it is still necessary to remove the foam slab, after cutting, from its assembly line or storage place and place it on a flat plate at which time the Wohler device may be utilized to effect the R.M.A. compression test. Additionally, test apparatus must be applied from the top and the process is relatively slow in that weights must be added at increments until the scale indicated 3/4 of the thickness is reached.